Apparatus and a Method of Forming a Particle Shield

ABSTRACT

An apparatus for generating at least one particle shield in photolithography includes a first component and a second component. The first component and the second component are operable to form a first particle shield of the at least one particle shield for blocking particles from contacting a proximate surface of an object. The first component includes a first gas injector, and the second component includes a first gas extractor corresponding to the first gas injector. The first gas injector is configured to blow out a gas, thereby forming the first particle shield. The first gas extractor is configured to work with the first gas injector for providing gas pressure gradient for the first particle shield.

PRIORITY CLAIM

This is a continuation application of U.S. patent application Ser. No.15/399,180, filed Jan. 5, 2017, which claims benefits of U.S. Prov. App.Ser. No. 62/351,764, filed Jun. 17, 2016, the entire content of which isincorporated by reference herein.

BACKGROUND

Semiconductor manufacturing includes various processes such asphotolithography, etching, and diffusion. Functional density hasincreased by decreasing a geometric size of components for integratedchips. Such scaling down process enhances production efficiency andlowers associated manufacturing costs. Removing debris and by-productsfrom equipment, photomasks and wafers helps to improve production yield.

In some approaches, a cleaning solvent such as deionized water issprayed on a surface to remove particles accumulated on the surface. Insome approaches, a solid shield is installed on a wafertransportation/storage pad during the manufacturing processes. In someapproaches, loading and unloading of wafers are performed automaticallyby a sealed input/output tool such as a standard mechanical interface(SMIF) apparatus. In some approaches, clothing of a process operator iscleaned to reduce contamination from particles introduced into amanufacturing environment.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A is a top view of an apparatus for generating a particle shieldin accordance with one or more embodiments.

FIG. 1B is a cross-sectional view of the apparatus for generating theparticle shield taken along line B-B′ in FIG. 1A in accordance with oneor more embodiments.

FIG. 1C is a top view of an apparatus for generating a plurality ofparticle shields in accordance with one or more embodiments.

FIG. 1D is a top view of an apparatus for generating a particle shieldin accordance with one or more embodiments.

FIG. 2A is a top view of an apparatus for generating a particle shieldin accordance with one or more embodiments.

FIG. 2B is a cross-sectional view of the apparatus for generating theparticle shield taken along line B-B′ in FIG. 2A in accordance with oneor more embodiments.

FIG. 2C is a cross-sectional view of an apparatus for generating aparticle shield in accordance with one or more embodiments.

FIG. 3 is a schematic cross-sectional view of an apparatus forgenerating a particle shield in accordance with one or more embodiments.

FIG. 4 is a schematic view of a photolithography system in accordancewith one or more embodiments.

FIG. 5 is a schematic view of a photolithography system in accordancewith one or more embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components, values, operations, materials,arrangements, or the like, are described below to simplify the presentdisclosure. These are, of course, merely examples and are not intendedto be limiting. Other components, values, operations, materials,arrangements, or the like, are contemplated. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Photolithography is a process by which a pattern on a photomask istransferred to a substrate or a layer on the substrate. The photomask, aframe and a pellicle are collectively referred to as a mask system. Theframe holds the photomask and the pellicle comprises a transparent thinfilm over the frame. The pellicle protects the photomask and helps toprevent particles from entering a focal point of light passing throughthe photomask. Particles are introduced into the photolithographyapparatus due to the removal of the photomask from a chuck, or materialremoval from the substrate or the layer on the substrate, or by othercontaminants present in the manufacturing environment. Particles in anoptical path of light passing through the photomask disperse light whichis incident on the particles. This light dispersion degrades the qualityof the pattern imparted by the light beam through the photomask. Theparticles also adhere on surfaces of the substrate (or the layer on thesubstrate), manufacturing equipment or measuring system. Particles onthe substrate or on the layer of the substrate potentially block lightfrom the photomask from being incident on the substrate (or the layer onthe substrate) and prevent precise transfer of the pattern of thephotomask. Particles on a surface of manufacturing equipment ormeasuring system also potentially disperse light contacting thoseelements and reduce precision of the pattern transfer. In at least oneembodiment, a shielding apparatus helps prevent particles from adheringto the surfaces or removes the particles from the surfaces or theoptical path during the manufacturing processes and, in turn, improvesmanufacturing yield.

FIG. 1A is a top view of an apparatus 100 for generating a particleshield 130, also referred to as a particle shield generator, inaccordance with one or more embodiments. Apparatus 100 includes a firstcomponent 110 and a second component 120. Apparatus 100 is configured togenerate particle shield 130 between first component 110 and secondcomponent 120. In order to help prevent particles or contaminants fromfalling onto or contacting a surface 140S of an object 140, particleshield 130 (symbolized by arrows) overlaps and is physically separatedfrom surface 140S. In some embodiments, particle shield 130 is invisibleto the human eye. In some embodiments, object 140 is a substrate, aphotomask, a wafer, or an inner wall of a carrier. In some embodiments,the substrate or the wafer includes one or more additional layer overthe substrate or the wafer. In some embodiments, the combination of thesubstrate and the additional layer is collectively referred to as thesubstrate. In some embodiments, the combination of the wafer and theadditional layer is collectively referred to as the wafer. In someembodiments, object 140 is a selected component in a manufacturingsystem, such as a reticle edge masking assembly (REMA), an illuminationaperture or a lens in a scanner system. In some embodiments, surface140S has a rectangular shape defined by a length L0 and a width W0,corresponding to a length L1 and a distance D1 of particle shield 130.In order to substantially cover surface 140S, length L1 is equal to orlonger than length L0, and distance D1 is equal to or longer than widthW0. As a result, an area of particle shield 130 is equal to or greaterthan an area of surface 140S. In some embodiments, length L1 anddistance D1 range between from about 127 millimeters (mm) to about 305mm. Longer length L1 or longer Distance D1 as well as shorter length L1or shorter distance D1 increase the difficulty of controlling particleshield 130, in some instances.

In some embodiments, both first component 110 and second component 120are fixed relative to surface 140S. In some embodiments, at least one offirst component 110 or second component 120 is movable relative tosurface 140S. In at least one embodiment, a movement is along adirection X, which is parallel to distance D1. In at least oneembodiment, a movement is along a direction Y, which is parallel tolength L1. Direction X and direction Y are parallel to surface 140S. Alongitudinal axis of first component 110 is parallel to a longitudinalaxis of second component 120. In some embodiments, the longitudinal axisof first component 110 and the longitudinal axis of second component 120are parallel to surface 140S. In some embodiments, at least one of firstcomponent 110 or second component 120 is movable along a direction Zorthogonal to surface 140S.

In some embodiments, first component 110 and second component 120 arephysically coupled to each other, either directly or through otherhardware (not shown). In some embodiments, first component 110 andsecond component 120 are physically separated from each other. Apparatus100 includes first component 110 and second component 120 on oppositesides of object 140; however, in some embodiments, first component 110and second component 120 have a different arrangement with respect toobject 140 in order to protect other surfaces. In some embodiments,apparatus 100 also includes a third component 115 and a fourth component125. In some embodiments, third component 115 and fourth component 125are positioned transverse to first component 110 and second component120. In some embodiments, apparatus 100 is operable to form anadditional particle shield between third component 115 and fourthcomponent 125. In some embodiments, third component 115 and fourthcomponent 125 provide a redundant apparatus in case first component 110or second component 120 fails, in such a way, the additional particleshield is positioned to be substantially co-planar with particle shield130. In some embodiments, third component 115 and fourth component 125provide an additional particle shield to enhance the protection, in sucha way; the additional particle shield is above or below particle shield130. In some embodiments, first component 110 and second component 120are usable to form particle shield 130 simultaneously with thirdcomponent 115 and fourth component 125 forming the additional particleshield. In some embodiments, first component 110 and second component120 are usable to form particle shield 130 before or after thirdcomponent 115 and fourth component 125 forms the additional particleshield.

In some embodiments, at least one of the longitudinal axis of firstcomponent 110 or the longitudinal axis of second component 120 is tiltedrelative to surface 140S. An angle of the tilting ranges from greaterthan 0 degrees to about 45 degrees, which is adjustable based on thearea of surface 140S and a working environment. For example, when bottomportions of first component 110 and second component 120 are fixed andwidth W0 is greater than a distance between bottom portions of firstcomponent 110 and second component 120, the tilting angle would resultin a wider opening between top portions of first component 110 andsecond component 120. A large tilting angle causes a top view ofdistance D1 to be smaller than width W0, in some instances.

FIG. 1B is a cross-sectional view of apparatus 100 for generatingparticle shield 130 taken along line B-B′ in FIG. 1A in accordance withone or more embodiments. In some embodiments, first component 110includes at least a gas injector 112. In at least one embodiment, gasinjector 112 is called an air knife or an air jet. In some embodiments,particle shield 130 is blown out of gas injector 112 into a space by theCoanda effect, which describes an adherence of fluid when close to asurface, resulting in an asymmetric expansion. In some embodiments,particle shield 130 is formed by compressing or pumping a gas from gasinjector 112. In some embodiments, a gas supply is connected to gasinjector 112 by a connecting pipe (not shown). In some embodiments,particle shield is generated by a pressure difference between firstcomponent 110 and second component 120. Gas injector 112 injects andprovides fluid dynamic control of particle shield 130, a protective gasstream flowed into a space between first component 110 and secondcomponent 120. In some embodiments, particle shield 130 is a gas curtainincluding an inert gas such as argon or helium. In some embodiments,particle shield 130 includes ambient air, nitrogen, hydrogen, orcombinations thereof.

In some embodiments, second component 120 includes at least a gasextractor 122. In at least one instance, gas extractor 122 and gasinjector 112 are aligned at the same level in a direction Z, which isparallel to the normal line of surface 140S. In some embodiments, gasextractor 122 is above or below gas injector 112 in direction Z. In atleast one embodiment, gas extractor 122 draws particles output by gasinjector 112 as well as other particles which pass between gas injector112 and gas extractor 122. In some embodiments, gas extractor 122includes a vacuum. Gas injector 112 and gas extractor 122 work togetherto provide an adequate air pressure gradient, even in a vacuumenvironment, for particle shield 130 to help prevent particles orcontaminants from reaching surface 140S. In some embodiments, duringoperation, particle shield 130 is circulated through gas injector 112and gas extractor 122. In some embodiments, instead of gas extractor122, second component 120 optionally includes an air receiver forpassively receiving particle shield 130 formed by gas from gas injector112.

Particle shield 130 is separated from surface 140S by a spacing S1ranging from about 0.5 mm to about 30 centimeters (cm). Larger spacingS1 reduces a functionality of particle shield 130 because increasedspace between particle shield 130 and surface 140S will permit particlesto enter into spacing S1 from direction X or direction Y for a longerdistance, in some instances. Shorter spacing S1 increases a risk of acontact between particle shield 130 and surface 140S, in some instances.

Particle shield 130 has a thickness T1 above surface 140S. Thickness T1ranges from about 1 mm to about 90 mm. Due to a low density of particleshield 130, thicker thickness T1 reduces a functionality of particleshield 130, in some instances. In some embodiments, thickness T1 issubstantially uniformly distributed between first component 110 andsecond component 120. In some embodiments, thickness T1 increases fromfirst component 110 to second component 120.

In some embodiments, first component 110 includes two or more airinjectors 112 positioned side by side, i.e., along direction Y, or oneover another, i.e., along direction Z. In some embodiments, whenpositioned side by side, an outlet of each gas injector 112 is formed ina nozzle shape. In some embodiments, when positioned one over another,an outlet of each gas injector 112 is formed in a slot shape extendingin direction Y. In some embodiments, in order to provide additional gasextraction, second component 120 includes two or more gas extractors122.

FIG. 1C is a top view of an apparatus 100′ for generating a plurality ofparticle shields 130 a′, 130 b′, 130 c′, 130 d′ and 130 e′ in accordancewith one or more embodiments. Apparatus 100′ is similar to apparatus100, like elements have a same reference number with a prime symbol.First component 110′, corresponding to another embodiment of firstcomponent 110, includes plural gas injectors 112 a′, 112 b′, 112 c′, 112d′ and 112 e′, and second component 120′, corresponding to anotherembodiment of second component 120, includes gas extractor 122′. Pluralparticle shields 130 a′-130 e′ are generated between gas injectors 112a′-112 e′ and gas extractor 122′. In some embodiments, gas extractor122′ includes a plurality of gas extractors, where each gas extractorcorresponds to one of gas injectors 112 a′-112 e′. S1milar to apparatus100 in FIG. 1B, a combined area of particle shields 130 a′-130 e′ isequal to or greater than surface 140S′. In some embodiments, everyparticle shield 130 a′-130 e′ includes a same gas. In some embodiments,at least one of particles shields 130 a′-130 e′ includes a different gasfrom a gas of at least one other of particle shields 130 a′-130 e′.

FIG. 1D is a top view of an apparatus 100″ for generating a particleshield 130″ in accordance with one or more embodiments. Apparatus 100″is similar to apparatus 100, like elements have a same reference numberwith a double prime symbol. Apparatus 100″ includes a first component110″ and a second component 120″. First component 110″ and secondcomponent 120″ have a curved shape. Particle shield 130″ is generatedbetween first component 110″ and second component 120″. Particle shield130″ helps prevent contaminants from reaching a surface 140S″ of object140″. In some embodiments, surface 140S″ has a circular shape defined bya diameter W0″ and particle shield 130″ has an oval shape coveringsurface 140S″. A length L1” and a distance D 1″ are therefore determinedbased on surface 140S″. In order to substantially cover surface 140S″,each of length L1” and distance D1″ is equal to or longer than diameterW0″. For example, for a 300-mm (12 inches) wafer, each of length L1” anddistance D1” is equal to or greater than 300 mm (12 inches).

FIG. 2A is a top view of an apparatus 200 for generating a particleshield 230, also referred to as a particle shield generator, inaccordance with one or more embodiments. Apparatus 200 is similar toapparatus 100, like elements have a same reference number increased by100. Apparatus 200 includes a first component 210 and a second component220. Apparatus 200 is configured to generate particle shield 230 (bestseen in FIG. 2B) between first component 210 and second component 220.In at least one embodiment, particle shield 230 is a magnetic field. Insome embodiments, first component 210 and/or second component 220 haveelectromagnets or permanent magnets. In some embodiments, parameters inthe design of positioning, spacing and strength of particle shield 230configuration are computationally optimized based on electromagneticsand the dimensions of the surface area to be protected from particlecontamination. In some embodiments, length L2 ranges from about 127 mmto about 305 mm. In some embodiments, the magnetic strength ranges fromabout 0.5 to 1.4 (Tesla) or larger. The smaller magnetic strengthreduces a protective function of particle shield 230, in some instances.In some embodiments, particle shield 230 exerts a velocity dependentforce such as a Lorentz force caused by an interaction between themagnetic field and at least one moving charged particle.

A first force 250 and a second force 252 are in opposite directionsalong direction Y. Under the electromagnetic field Lorentz force, whenapproaching particle shield 230, charged particles or contaminants willbe driven away from an area of a surface 240S of an object 240 alongdirection Y. The Lorentz force is perpendicular to both a velocity ofthe charged particle and a magnetic field, i.e., particle shield 230,with direction given by the right hand rule. The force is given by thecharge times the vector product of velocity and magnetic field. Positivecharged particles are forced in a first direction and negative chargedparticles are forced in a second direction opposite the first direction.For example, when a negative charged particle contacts particle shield230, the negative charged particle is driven by second force 252. Insome embodiments, a length L2 of first component 210 is equal to orgreater than length L0 of surface 240S. A magnitude of first force 250or second force 252 is large enough to push charged particles away fromsurface 240S.

FIG. 2B is a cross-sectional view of apparatus 200 for generatingparticle shield 230 in accordance with one or more embodiments. In someembodiments, particle shield 230 comprises another energy gradientforce, such as a thermal gradient driving force generated by atemperature difference. In at least one instance, first component 210has a higher temperature than second component 220, resulting in aparticle movement from first component 210 to second component 220. Insome embodiments, first component 210 includes a North Pole magnet 212and second component 220 includes a South Pole magnet 222. Particleshield 230 is the magnetic field symbolized by arrows. In someembodiments, object 240 is encompassed in particle shield 230 so thatsurface 240S is closer to first component 210 and second component 220along direction Z.

FIG. 2C is a cross-sectional view of an apparatus 200′ for generatingone or more particle shields in accordance with one or more embodiments.In some embodiments, a combination of the energy gradient force and thevelocity dependent force is used to enhance protection from particles.For example, first component 210 including North Pole magnet 212 isabove first component 110 including gas injector 112; second component220 including South Pole magnet 222 is above second component 120. Insome embodiments, first component 110 and second component 120 are abovefirst component 210 and second component 220. Alternatively, firstcomponent 110 and second component 120 are positioned transverse tofirst component 210 and second component 220 similar to third component115 and fourth component 125 in apparatus 100. In contrast withapparatus 100, because there is no interaction between the gas andmagnetic field, particle shield 130 is co-planar with particle shield230, in some embodiments.

In some embodiments, both the energy gradient force and the velocitydependent force are generated from a same component. For example, firstcomponent 210 and second component 220 are used to generate an aircurtain as well as a magnetic field. One of ordinary skill in the artwould understand that first component 210 or second component is notlimited to an air curtain or a magnetic field. In at least oneembodiment, at least one of first component 210 and second component 220is used to generate an optical laser to burn the particles. In someembodiments, apparatus 200′ includes more than two particle shields,such as a combination of an air curtain, a magnetic field and a thermalgradient driving force.

FIG. 3 is an enlarged schematic view of an apparatus 300 for generatinga particle shield 330, also referred to as a particle shield generator,in accordance with one or more embodiments. Apparatus 300 is similar toapparatus 100, like elements having a same reference number increased by200. Apparatus 300 includes a first component 310. In some embodiments,first component 310 is a gas injector 312. Gas injector 312 generatesparticle shield 330, which includes an upper surface 330U and a lowersurface 330L. A thickness T3 of particle shield 330 is defined by adistance between upper surface 330U and lower surface 330L. In variousembodiments, a particle shield 330 provides an air curtain in directionX along width W0 to help block particles and thickness T3 is modified byseveral parameters such as gas density, molecular weight, and velocityof gas fluid. In some embodiments, thickness T3 ranges from about 1 mmto about 90 mm. For example, at an end of particle shield 330 extendingto 152 mm (6 inches), thickness T3 ranges from 25.4 mm to around 38.1mm. Due to a low density of particle shield 330, thicker thickness T3reduces a functionality of particle shield 330, in some instances. Insome embodiments, upper surface 330U is substantially tilted up and hasan angle ranging from about 5-degrees to about 11-degrees abovedirection X and lower surface 330L is parallel to a surface 340S.Incoming particles are pushed away from surface 340S. Due to a largegradient, particle shield 330 is likely to contact an edge of surface340S, in some instances. In order to help prevent lower surface 330L ofparticle shield 330 from contacting surface 340S, component 310 isdesigned to maintain a spacing S3 between lower surface 330L and surface340S and may be larger than a maximum value of thickness T3.

In comparison with apparatus 100, apparatus 300 does not include asecond component. The second component is omitted from apparatus 300because a force of the gas ejected from first component 312 issufficiently strong to block particles without the added assistance ofthe second component. In some embodiments, a device housing apparatus300 and surface 340S has an opening across from first component 312 topermit particles to be forced out of the device. In some embodiments,apparatus 300 includes the second component. In some embodiments, firstcomponent 312 is separated into multiple first components as inapparatus 100′ (FIG. 1C).

FIG. 4 is a schematic view of a photolithography system 400 inaccordance with one or more embodiments. Photolithography system 400includes an apparatus for generating a particle shield similar toapparatus 100 (or apparatus 100′, 100″, 200, 200′ and 300), last twodigits of like elements are the same. Photolithography system 400includes a photomask 440, a slit 442, a radiation source 444, aplurality of reflectors or mirrors 446 and 446′ and a set of apertures448 and 448′. A beam of optical energy 450 is generated by radiationsource 444, propagates along an optical path to reflectors 446, aperture448 and slit 442 to photomask 440. Optical energy 450 is reflected byphotomask 440, and propagates through slit 442, aperture 448′ andreflectors 446′. Reflectors 446′ reduce an image from photomask 440 forforming an image onto a wafer. In some embodiments, a distance betweenphotomask 440 and slit 442 ranges from about 10 mm to about 100 mm.Apparatus 400 includes a catoptric imaging system. In some embodiments,apparatus 400 includes a catadioptric imaging system.

Photolithography system 400 further includes a first component 410, asecond component 420, a third component 410′ and a fourth component420′. A first particle shield 430 is between first component 410 andsecond component 420. A second particle shield 432 is between thirdcomponent 410′ and fourth component 420′. First component 410 and secondcomponent 420 are between photomask 440 and slit 442. Third component410′ and fourth component 420′ are between slit 442 and apertures 448and 448′. Both first particle shield 430 and second particle shield 432help prevent particles or contaminants from adhering or falling ontophotomask 440 and/or slit 442. In some embodiments, both first particleshield 430 and second particle shield 432 include a gas stream. Forexample, first particle shield 430 and second particle shield 432includes hydrogen, ambient air, helium, nitrogen or inert gases. In someembodiments, first particle shield 430 and second particle shield 432include different gases. In some embodiments, a size of first particleshield 430 and second particle shield 432 ranges from four inches byfour inches to six inches by six inches. In some embodiments, a size offirst particle shield 430 and second particle shield 432 is greater thansix inches by six inches. In some instances, a greater size of firstparticle shield 430 increases a size of photomask container. In someinstances, a greater size of first particle shield 430 cannot fit inphotolithography system 400. A smaller size causes the coverage forphotomask 440 to be insufficient to block particles from contactingphotomask 440. In some embodiment, a thickness of first particle shield430 and second particle shield 432 ranges from about 1 mm to about 35mm. In some embodiments, first particle shield 430 and second particleshield 432 include a combination of the energy gradient force and thevelocity dependent force. For example, first particle shield 430includes a gas and second particle shield 432 includes anelectromagnetic Lorenz force. In various embodiments, depending on arequirement of cleanliness, one or more sets of components forgenerating particles shields are positioned proximate a surface of anyof radiation source 444, reflectors 446, 446′, apertures 448, 448′ orthe wafer. In some embodiments, photolithography system 400 includesapparatus 100, 100′, 100″, 200, 200′, 300, or combinations therefor.

In some embodiments, photolithography system 400 is an extremeultraviolet (EUV) exposure scanner and slit 442 is a REMA. In someinstances, photomask 440 is also called a reticle or a mask. In someembodiments, radiation source 444 is created by plasma when a laserilluminates a gas, such as a supersonic jet of xenon gas. For example,radiation source 444 provides EUV radiation having a wavelength ofapproximately 13.5 nm. In some embodiments, when first particle shield430 and second particle shield 432 include gas, a transmission lossbetween the beam of optical energy 450 and 450′ ranges from about 0.011%to about 0.022%. In some embodiments, the gas has a low absorption ofoptical energy 450. A greater transmission loss reduces the exposure oflayout patterns on the wafer. In some embodiments, photolithographysystem 400 is an X-Ray lithography, an ion beam projection lithography,or an electron-beam projection lithography.

FIG. 5 is a schematic view of a photolithography system 500 inaccordance with one or more embodiments. Photolithography system 500includes an apparatus similar to apparatus for generating a particleshield 100 (or apparatus 100′, 100″, 200, 200′ and 300), last two digitsof like elements having a same reference number are the same.Photolithography system 500 includes a photomask 540, a lens 542, aradiation source 544, an imaging module 546 and fluid 560. A firstcomponent 510, a second component 520 and a first particle shield 530are between radiation source 544 and lens 542. A third component 510′, afourth component 520′ and a second particle shield 530′ are between lens542 and photomask 540. A fifth component 510″, a sixth component 520″and a third particle shield 530″ are between photomask 540 and imagingmodule 546. Radiation source 544 emits a beam of optical energy 550through first particle shield 530 and lens 542. A beam of optical energy550′ is then passed through second particle shield 530′ and photomask540. A beam of optical energy 550″ is then passed through third particleshield 530″ and imaging module 546. A fluid 560 fills at least a spacebetween imaging module 546 and a wafer 570. In some embodiments, each offirst particle shield 530, second particle shield 530′ and thirdparticle shield 530″ independently includes a gas fluid or the velocitydependent force. In some embodiments, photolithography system 500includes apparatus 100, 100′, 100″, 200, 200′, 300, or combinationstherefor.

In some embodiments, photolithography system 500 is an immersionphotolithography system. In some embodiments, similar tophotolithography system 400, each of first particle shield 530, secondparticle shield 530′ and third particle shield 530″ include the energygradient force, the velocity dependent force, or combinations thereof.In at least one embodiment, when first particle shield 530, secondparticle shield 530′ and third particle shield 530″ consist of gasfluid, a photon transmission loss between the beam of optical energy 550and 550′ ranges from about 0.011% to about 0.033%. In variousembodiments, depending on a requirement of cleanliness, one or more setsof components are positioned on selected surfaces in photolithographysystem 500.

In some embodiments, apparatus 100, 100′, 100″, 200, 200′, 300 isarranged above selected surface during other manufacturing process line,such as a standard mechanical interface (SMIF) pod station or a spectracritical dimension equipment, photoresist spinner, or wet spray etcher.

One aspect of this description relates to an apparatus for generating aplurality of particle shields. The at least one particle shield includesa first component and a second component. The first component and thesecond component are usable to form a first particle shield of the atleast one particle shield for blocking particles from contacting aproximate surface of an object, the first particle shield issubstantially parallel to and physically separated from the proximatesurface of the object, and the first particle shield includes an energygradient force or a velocity gradient force.

Another aspect of this description relates to a photolithography system.The photolithography system includes a photomask, a slit, at least oneoptical element, a first apparatus generating a first particle shield,and a second apparatus generating a second particle shield, wherein theslit is between the first particle shield and the second shield.

Still another aspect of this description relates to a method forphotolithography in semiconductor manufacturing. The method includespositioning a shield generator between a photomask and a slit, forming aparticle shield by the shield generator to help prevent particles fromadhering to a surface of the photomask or a surface of the slit, andremove the particles along an optical path, wherein the shield generatoris between the photomask and the slit, and performing an exposure totransfer one or more patterns in the photomask onto a substrate or alayer on the substrate.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An apparatus for generating at least one particle shield in photolithography, comprising: a first component and a second component, wherein the first component and the second component are operable to form a first particle shield of the at least one particle shield for blocking particles from contacting a proximate surface of an object, wherein the first component includes a first gas injector, and the second component includes a first gas extractor corresponding to the first gas injector, wherein the first gas injector is configured to blow out a gas, thereby forming the first particle shield, and wherein the first gas extractor is configured to work with the first gas injector for providing gas pressure gradient for the first particle shield.
 2. The apparatus of claim 1, wherein the first gas injector and the first gas extractor are aligned at a same level in a direction parallel to normal of the proximate surface of the object.
 3. The apparatus of claim 1, wherein the first gas injector is above or below the first gas extractor in a direction parallel to normal of the proximate surface of the object.
 4. The apparatus of claim 1, wherein the first gas extractor includes a vacuum.
 5. The apparatus of claim 1, wherein the first gas extractor is configured to draw particles output by the first gas injector.
 6. The apparatus of claim 1, wherein the first gas injector and the first gas extractor are configured such that the first particle shield is circulated through the first gas injector and the first gas extractor.
 7. The apparatus of claim 1, wherein an area of the first particle shield is greater than an area of the proximate surface.
 8. The apparatus of claim 1, wherein the first particle shield is separated from the proximate surface of the object by a spacing ranging from 0.5 mm to 30 cm.
 9. The apparatus of claim 1, wherein the first particle shield has a thickness ranging from 1 mm to 90 mm.
 10. The apparatus of claim 1, wherein the first component includes a second gas injector and the second component includes a second gas extractor corresponding to the second gas injector, wherein the second gas injector and the second gas extractor are operable to form a second particle shield of the at least one particle shield for blocking particles from contacting the proximate surface of an object.
 11. The apparatus of claim 10, wherein the first and second gas injectors are positioned side by side along a direction parallel to the proximate surface of the object.
 12. The apparatus of claim 10, wherein the first and second gas injectors are positioned one over another along a direction parallel to normal of the proximate surface of the object.
 13. The apparatus of claim 1, wherein at least one of the first and second components is movable relative to the proximate surface of the object.
 14. An apparatus for generating at least one particle shield in photolithography, comprising: a first component and a second component, wherein the first component and the second component are operable to form a first particle shield of the at least one particle shield for blocking particles from contacting a proximate surface of an object, wherein the first particle shield includes an energy gradient force or a velocity dependent force; and a third component and a fourth component, wherein the third component and the fourth component are operable to form a second particle shield of the at least one particle shield for blocking particles from contacting the proximate surface of the object, wherein the second particle shield includes an energy gradient force or a velocity dependent force, wherein the first component includes a first gas injector, and the second component includes a first gas extractor corresponding to the first gas injector, wherein the first gas injector is configured to blow out a gas, thereby forming the first particle shield, and wherein the first gas extractor is configured to work with the first gas injector for providing gas pressure gradient for the first particle shield.
 15. The apparatus of claim 14, wherein the second component is parallel with the first component, the fourth component is parallel with the third component, and the third component and the fourth component are transverse to the first component and the second component.
 16. The apparatus of claim 14, wherein the second particle shield includes one of: an air curtain, a thermal gradient driving force, an electromagnetic Lorenz force, and an optical laser.
 17. A photolithography system comprising: a slit; a first component and a second component operable for generating a first particle shield for blocking particles from contacting a proximate surface of a photomask; and a third component and a fourth component operable for generating a second particle shield, wherein the slit is between the first particle shield and the second particle shield, wherein the first component includes a first gas injector, and the second component includes a first gas extractor corresponding to the first gas injector, wherein the first gas injector is configured to blow out a gas, thereby forming the first particle shield, and wherein the first gas extractor is configured to work with the first gas injector for providing gas pressure gradient for the first particle shield.
 18. The photolithography system of claim 17, wherein an area of the first particle shield is equal to or greater than six inches by six inches.
 19. The photolithography system of claim 17, wherein a thickness of the first particle shield ranges from 1 millimeter (mm) to 35 mm.
 20. The photolithography system of claim 17, further comprising: a radiation source; an optical aperture; and a reflector, wherein a beam of optical energy generated from the radiation source propagates along an optical path to the reflector, the optical aperture, the second particle shield, the slit, the first particle shield, and the photomask. 